The Coastal Cave consists mostly of puzzles centred around destroyable blocks. Destroying them in the incorrect order will often force the player to renew the puzzle by exiting the room and reentering. Among the other puzzles present are swinging iron balls, which are tethered to a destroyable stone pole. Destroying the poll releases the metal sphere on a trajectory tangential to its swing at the point of release, until it strikes a wall. Provided it comes to rest in the right place, the ball can then be used as a step or platform to continue deeper into the dungeon.

Among the various treasures of the cave are the Merman Boots, which allow Alundra to swim in water. These are required to access the latter half of the cave, which focuses on jumping courses, mainly over water with many floating hazards floating.

The cave appears to have been inhabited at some point, as a bridge and even a prison are present, as well as signage to denote this. In the deepest recess of the cave, a water-based creature dwells, guarding the resting place of the Guardian Vul. It is ashamed that it allowed the Murgg to enter and steal the Crest within, and so attacks Alundra without thought.

After Alundra defeats the Watcher in the Water, he meets Vul's spirit, who explains what the Murgg have done, and grants Alundra the Water Scroll, before sending him back to the entrance to the cave.